This invention relates to liquid transport systems, and especially to sequential transportation of multiple products through a single transport system defined by one or more pipes or tubes. More specifically, this invention relates to distribution of liquids from one or more source nodes in the liquid transport system to one or more destination nodes in the liquid transport system.
This invention relates especially to removing and/or cleaning product liquid from the pipeline system upon completion of the transport of one product through the pipeline system, and before commencing transport of the next product through the pipeline system.
This invention further relates to methods and apparatus for cleaning in place a pipeline system which transports food or other liquid product from a source node in the pipeline system to a destination node in the pipeline system.
Sanitation in the food processing industry is critical to maintaining purity of the food supply. Accordingly, where more than one food product is transported through a pipeline system, it is necessary to clean the pipeline system between the transport of a first food product and the transport of a second different food product through the same pipeline system.
Where the frequency of changes between different food products is infrequent, it is common to disassemble the pipeline system and clean each component individually. Where the frequency of changes is relatively more frequent, the incremental cost of such disassembly and cleaning between products can be prohibitively costly as to a given product, which may dictate against the cost effectiveness of producing relatively smaller quantities of a given product whereby other aspects of the production/distribution system may be adversely affected.
One solution to the process of cleaning the pipeline, without disassembly of the pipeline system, is to install a pigging system whereby a pig is forced through the pipeline from an entrance locus to a destination locus in the pipeline. As the pig is forced through the pipeline, the pig cleans residual material from the pipeline thus to leave the pipeline system generally cleaned and ready to receive the next product.
Pigging systems are generally known for use between the transport of related products in a pipeline system. Pigging systems are represented generally by U.S. Pat. No. 3,665,954 McNeal et al. McNeal et al teach pushing a pig through a relatively shorter pipeline, from a source node 15 to a destination node 9, using compressed air, thus to push a final portion of the product to the destination node, and accordingly into the representative truck. The pipeline is thus cleaned of product, and is empty, and the pig is returned along the same pipeline to a starting locus beyond the source node, and out of the line of travel of the product liquid.
Another pigging system, useful for cleaning a portion of a pipeline which is used in transporting petroleum products sequentially, is taught in U.S. Pat. No. 3,135,278 Foord et al. Foord et al teach use of a closed loop system of piping 1, 2, and 11 to transport liquid from a first tank to a destination. After completion of transporting the first product from the source node to the destination node, a pig is forced between first and second traps by a second product liquid, to clean a portion, but not substantially all, of the first product from the pipeline system. Indeed, a portion of the first product liquid remains in the pipeline system, in one or more main paths by which the second liquid is transported through the pipeline system to the destination node. Since less than substantially all of the first product liquid is removed from the pipeline system by the pigging operation, the second product liquid ultimately mixes with the remainder portion of the first product as the second product is being transported to the destination node. While Foord et al provide generally for a partial removal of that portion of the first product which remains in the pipeline after completion of the first product transport step, Foord et al do not provide for any cleaning of the pipeline before introduction of the second product into the pipeline system. Neither do Foord et al provide for cleaning of substantially all of the first product from the pipeline system before introduction of the second product into the pipeline system, and transport of the second product from a source node to a destination node.
It is an object of this invention to provide liquid transport systems which provide closed loop pipelines having multiple source/destination nodes connected to an endless loop of piping, wherein a first product liquid can be substantially cleaned from the closed loop of piping before a second product liquid is introduced into the closed loop of piping.
It is an object to provide liquid transport systems which contain at least product source/destination nodes connected to the endless loop of piping.
It is another object to provide such endless loop of piping with a cleaning system comprising at least one of a compressed gas inlet and a non-product liquid inlet, and a cleaning manifold which is disposed between first and second pig launchers, and wherein the pig launchers are between the cleaning manifold and all except no more than one of the source/destination nodes.
It is yet another object to provide such endless loop of piping wherein each product source/destination node is connected to a single product source structure or a single destination structure outside the endless loop of piping.
It is still another object to provide such endless loop of piping wherein a node control valve is disposed at or adjacent each product source/destination node, less no more than one node, wherein the node control valves are effective to control flow of liquid through the respective nodes and into or out of the endless loop of piping.